Enable ES6 iteration by default

test/mjsunit/harmony/iteration-semantics.js

-// Copyright 2013 the V8 project authors. All rights reserved.
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-//       notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-//       copyright notice, this list of conditions and the following
-//       disclaimer in the documentation and/or other materials provided
-//       with the distribution.
-//     * Neither the name of Google Inc. nor the names of its
-//       contributors may be used to endorse or promote products derived
-//       from this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// Flags: --harmony-iteration
-// Flags: --harmony-generators --harmony-scoping --harmony-proxies
-
-// Test for-of semantics.
-
-"use strict";
-
-
-// First, some helpers.
-
-function* values() {
-  for (var i = 0; i < arguments.length; i++) {
-    yield arguments[i];
-  }
-}
-
-function wrap_iterator(iterator) {
-    var iterable = {};
-    iterable[Symbol.iterator] = function() { return iterator; };
-    return iterable;
-}
-
-function integers_until(max) {
-  function next() {
-    var ret = { value: this.n, done: this.n == max };
-    this.n++;
-    return ret;
-  }
-  return wrap_iterator({ next: next, n: 0 });
-}
-
-function results(results) {
-  var i = 0;
-  function next() {
-    return results[i++];
-  }
-  return wrap_iterator({ next: next });
-}
-
-function* integers_from(n) {
-  while (1) yield n++;
-}
-
-// A destructive append.
-function append(x, tail) {
-  tail[tail.length] = x;
-  return tail;
-}
-
-function sum(x, tail) {
-  return x + tail;
-}
-
-function fold(cons, seed, iterable) {
-  for (var x of iterable) {
-    seed = cons(x, seed);
-  }
-  return seed;
-}
-
-function* take(iterable, n) {
-  if (n == 0) return;
-  for (let x of iterable) {
-    yield x;
-    if (--n == 0) break;
-  }
-}
-
-function nth(iterable, n) {
-  for (let x of iterable) {
-    if (n-- == 0) return x;
-  }
-  throw "unreachable";
-}
-
-function* skip_every(iterable, n) {
-  var i = 0;
-  for (let x of iterable) {
-    if (++i % n == 0) continue;
-    yield x;
-  }
-}
-
-function* iter_map(iterable, f) {
-  for (var x of iterable) {
-    yield f(x);
-  }
-}
-function nested_fold(cons, seed, iterable) {
-  var visited = []
-  for (let x of iterable) {
-    for (let y of x) {
-      seed = cons(y, seed);
-    }
-  }
-  return seed;
-}
-
-function* unreachable(iterable) {
-  for (let x of iterable) {
-    throw "not reached";
-  }
-}
-
-function one_time_getter(o, prop, val) {
-  function set_never() { throw "unreachable"; }
-  var gotten = false;
-  function get_once() {
-    if (gotten) throw "got twice";
-    gotten = true;
-    return val;
-  }
-  Object.defineProperty(o, prop, {get: get_once, set: set_never})
-  return o;
-}
-
-function never_getter(o, prop) {
-  function never() { throw "unreachable"; }
-  Object.defineProperty(o, prop, {get: never, set: never})
-  return o;
-}
-
-function remove_next_after(iterable, n) {
-  var iterator = iterable[Symbol.iterator]();
-  function next() {
-    if (n-- == 0) delete this.next;
-    return iterator.next();
-  }
-  return wrap_iterator({ next: next });
-}
-
-function poison_next_after(iterable, n) {
-  var iterator = iterable[Symbol.iterator]();
-  function next() {
-    return iterator.next();
-  }
-  function next_getter() {
-    if (n-- < 0)
-      throw "poisoned";
-    return next;
-  }
-  var o = {};
-  Object.defineProperty(o, 'next', { get: next_getter });
-  return wrap_iterator(o);
-}
-
-// Now, the tests.
-
-// Non-generator iterators.
-assertEquals(45, fold(sum, 0, integers_until(10)));
-// Generator iterators.
-assertEquals([1, 2, 3], fold(append, [], values(1, 2, 3)));
-// Break.
-assertEquals(45, fold(sum, 0, take(integers_from(0), 10)));
-// Continue.
-assertEquals(90, fold(sum, 0, take(skip_every(integers_from(0), 2), 10)));
-// Return.
-assertEquals(10, nth(integers_from(0), 10));
-// Nested for-of.
-assertEquals([0, 0, 1, 0, 1, 2, 0, 1, 2, 3],
-             nested_fold(append,
-                         [],
-                         iter_map(integers_until(5), integers_until)));
-// Result objects with sparse fields.
-assertEquals([undefined, 1, 2, 3],
-             fold(append, [],
-                  results([{ done: false },
-                           { value: 1, done: false },
-                           // A missing "done" is the same as undefined, which
-                           // is false.
-                           { value: 2 },
-                           // Not done.
-                           { value: 3, done: 0 },
-                           // Done.
-                           { value: 4, done: 42 }])));
-// Results that are not objects.
-assertEquals([undefined, undefined, undefined],
-             fold(append, [],
-                  results([10, "foo", /qux/, { value: 37, done: true }])));
-// Getters (shudder).
-assertEquals([1, 2],
-             fold(append, [],
-                  results([one_time_getter({ value: 1 }, 'done', false),
-                           one_time_getter({ done: false }, 'value', 2),
-                           { value: 37, done: true },
-                           never_getter(never_getter({}, 'done'), 'value')])));
-
-// Unlike the case with for-in, null and undefined cause an error.
-assertThrows('fold(sum, 0, unreachable(null))', TypeError);
-assertThrows('fold(sum, 0, unreachable(undefined))', TypeError);
-
-// Other non-iterators do cause an error.
-assertThrows('fold(sum, 0, unreachable({}))', TypeError);
-assertThrows('fold(sum, 0, unreachable(false))', TypeError);
-assertThrows('fold(sum, 0, unreachable(37))', TypeError);
-
-// "next" is looked up each time.
-assertThrows('fold(sum, 0, remove_next_after(integers_until(10), 5))',
-             TypeError);
-// It is not called at any other time.
-assertEquals(45,
-             fold(sum, 0, remove_next_after(integers_until(10), 10)));
-// It is not looked up too many times.
-assertEquals(45,
-             fold(sum, 0, poison_next_after(integers_until(10), 10)));
-
-function labelled_continue(iterable) {
-  var n = 0;
-outer:
-  while (true) {
-    n++;
-    for (var x of iterable) continue outer;
-    break;
-  }
-  return n;
-}
-assertEquals(11, labelled_continue(integers_until(10)));
-
-function labelled_break(iterable) {
-  var n = 0;
-outer:
-  while (true) {
-    n++;
-    for (var x of iterable) break outer;
-  }
-  return n;
-}
-assertEquals(1, labelled_break(integers_until(10)));
-
-// Test continue/break in catch.
-function catch_control(iterable, k) {
-  var n = 0;
-  for (var x of iterable) {
-    try {
-      return k(x);
-    } catch (e) {
-      if (e == "continue") continue;
-      else if (e == "break") break;
-      else throw e;
-    }
-  } while (false);
-  return false;
-}
-assertEquals(false,
-             catch_control(integers_until(10),
-                           function() { throw "break" }));
-assertEquals(false,
-             catch_control(integers_until(10),
-                           function() { throw "continue" }));
-assertEquals(5,
-             catch_control(integers_until(10),
-                           function(x) {
-                             if (x == 5) return x;
-                             throw "continue";
-                           }));
-
-// Test continue/break in try.
-function try_control(iterable, k) {
-  var n = 0;
-  for (var x of iterable) {
-    try {
-      var e = k(x);
-      if (e == "continue") continue;
-      else if (e == "break") break;
-      return e;
-    } catch (e) {
-      throw e;
-    }
-  } while (false);
-  return false;
-}
-assertEquals(false,
-             try_control(integers_until(10),
-                         function() { return "break" }));
-assertEquals(false,
-             try_control(integers_until(10),
-                         function() { return "continue" }));
-assertEquals(5,
-             try_control(integers_until(10),
-                         function(x) { return (x == 5) ? x : "continue" }));
-
-// Proxy results, with getters.
-function transparent_proxy(x) {
-  return Proxy.create({
-    get: function(receiver, name) { return x[name]; }
-  });
-}
-assertEquals([1, 2],
-             fold(append, [],
-                  results([one_time_getter({ value: 1 }, 'done', false),
-                           one_time_getter({ done: false }, 'value', 2),
-                           { value: 37, done: true },
-                           never_getter(never_getter({}, 'done'), 'value')]
-                          .map(transparent_proxy))));
-
-// Proxy iterators.
-function poison_proxy_after(iterable, n) {
-  var iterator = iterable[Symbol.iterator]();
-  return wrap_iterator(Proxy.create({
-    get: function(receiver, name) {
-      if (name == 'next' && n-- < 0) throw "unreachable";
-      return iterator[name];
-    },
-    // Needed for integers_until(10)'s this.n++.
-    set: function(receiver, name, val) {
-      return iterator[name] = val;
-    }
-  }));
-}
-assertEquals(45, fold(sum, 0, poison_proxy_after(integers_until(10), 10)));